Add concurrency control to cancel stale PR workflow runs (#271)

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: letmaik <530988+letmaik@users.noreply.github.com>
Co-authored-by: Maik Riechert <letmaik@outlook.com>

Author: Copilot

.github/workflows/ci.yml

@@ -30,6 +30,10 @@ on: [push, pull_request, workflow_dispatch]
 
 permissions: read-all
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
 jobs:
   build:
     strategy: